Environmental control system fluid sensing system and method

• US 7,350,367 B2
• Filed: 09/27/2004
• Issued: 04/01/2008
• Est. Priority Date: 10/18/2002
• Status: Active Grant

• Current Assignee: Meas France
• Original Assignee: Visyx Technologies, Inc. (TE Connectivity Ltd. (United Kingdom))
• Inventors: Varni, John F., Matsiev, Leonid, Kolosov, Oleg, Feland, John M. III, Walker, Blake, Rust, William, Uhrich, Mark D.
• Primary Examiner(s): Norman; Marc
• Application Number:
  US10/951,252
• Publication Number:
  US 20050145019A1
• Time in Patent Office: 1,282 Days
• Field of Search: 621/25, 621/26, 621/29, 621/31, 622/25, 73/10, 73/530.1, 73/240.1, 73/240.4, 73/240.6, 73/544.1, 702/50
• US Class Current: 62/129
• CPC Class Codes: G01N 11/16 by measuring damping effect upon oscillatory body
• CPC Class Codes: G01N 2009/006 vibrating tube, tuning fork
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/0226 Oils, e.g. engine oils
• CPC Class Codes: G01N 2291/0253 Condensation
• CPC Class Codes: G01N 2291/0254 Evaporation
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/223 Supports, positioning or alignment in fixed situation mounting transducers per se G10K11/004
• CPC Class Codes: G01N 29/228 related to high temperature conditions
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: G01N 29/343 pulse waves, e.g. particular sequence of pulses, bursts
• CPC Class Codes: G01N 9/002 using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis G01N9/34 takes precedence

Abstract

A system for monitoring a fluid in an environmental control system includes a mechanical resonator positioned for contacting a thermal change fluid. In some embodiments, the mechanical resonator is positioned in a passage for containing the thermal change fluid. Suitable thermal change fluids include an R-134A refrigerant, a mineral oil, an ester lubricant or a mixture thereof; a superheated refrigerant; or an elevated pressure and elevated temperature vapor, an elevated pressure liquid, a reduced pressure liquid, a reduced pressure vapor and combinations thereof. The mechanical resonator can be a flexural resonator or a torsion resonator. In some embodiments, the mechanical resonator is a tuning fork resonator. Methods of the invention include monitoring a response of the mechanical resonator to the thermal change fluid. In some embodiments, at least a portion of the mechanical resonator is translated through the thermal change fluid and the response of the resonator to the fluid is monitored.

Claims

1. A method for monitoring a thermal change fluid in an environmental control system, the method comprising

operating a mechanical resonator in an environmental control system selected from heating, ventilation, air conditioning and refrigeration systems, the environmental control system including a passage for a thermal change fluid, the mechanical resonator being a flexural resonator, a torsional resonator or a combination thereof,

translating at least a portion of the resonator through the thermal change fluid, the thermal change fluid comprising R-134A refrigerant, a mineral oil, an ester lubricant or a mixture thereof, and

monitoring the response of the resonator to the thermal change fluid in the passage.

7. The method of claims 1, 2 or 4 wherein the resonator is coated over at least a portion of its outer surface.

8. The method of claims 1, 2 or 4 wherein the resonator comprises a resonator element made of a piezoelectric material.

9. The method of claims 1, 2 or 4 wherein the resonator comprises a resonator element made of lithium niobate.

11. The method of claims 1, 2 or 4 wherein the resonator is selected from tuning forks, cantilevers, unimorphs, bimorphs, membrane resonators, torsion bars or combinations thereof.

12. The method of claims 1, 2 or 4 wherein the resonator is a tuning fork resonator.

13. The method of claims 1, 2 or 4 wherein the resonator is a piezoelectric tuning fork resonator.

14. The method of claims 1, 2 or 4 wherein the resonator is operated at frequencies of less than about 1 MHz.

15. The method of claims 1, 2 or 4 further comprising the step of employing data obtained from the monitoring step to perform at least one operation of the environmental control system or a component thereof.

16. The method of claim 15 wherein the at least one operation of the environmental control system is selected from switching the environmental control system or one or more components therein to an on or off state, closing or opening a valve in the environmental control system, changing a flow rate of the thermal change fluid or refrigerant, changing a pressure of the thermal change fluid or refrigerant, changing the operating speed or condition of one or more components of the environmental control system, providing a visual output signal, providing an audible output signal, or a combination thereof.

17. The method of claims 1, 2 or 4 wherein the monitoring step comprises monitoring at least one of fluid viscosity, fluid density, fluid conductivity, fluid viscosity/density product, or fluid dielectric constant.

18. The method of claim 1, 2 or 4 wherein the monitoring step further comprises a step selected from monitoring a change of frequency of the resonator while maintaining an input signal to the resonator as a constant, monitoring the change in electrical feedback from the resonator while maintaining the input signal to the resonator as a constant, varying the frequency of a variable frequency input signal over a predetermined frequency range to obtain a frequency-dependent resonator response of the resonator, comparing the response of the resonator with a prior response of the resonator, comparing the response of the resonator with a known reference value for the thermal change fluid, comparing the response of the resonator with the response of another resonator in the system, or a combination of two or more such steps.

2. A method for monitoring a superheat condition of a refrigerant in an environmental control system, the method comprising

superheating a refrigerant in an environmental control system, and

monitoring the superheated refrigerant with a mechanical resonator.

3. The method of claim 2 wherein the refrigerant further comprises refrigerant lubricant.

10. The method of claims 2 or 4 wherein the mechanical resonator is a flexural resonator, a torsional resonator or a combination thereof.

19. The method of claims 2 or 4 wherein the environmental control system is an air conditioning or refrigeration system.

4. A method for monitoring a fluid in an environmental control system, the method comprising

pressurizing and heating a reduced pressure vapor in an environmental control system to form an elevated pressure, elevated temperature vapor,

condensing the elevated pressure, elevated temperature vapor to form an elevated pressure liquid,

expanding the elevated pressure liquid to form a reduced pressure liquid,

evaporating the reduced pressure liquid to form a reduced pressure vapor, and

monitoring a fluid selected from one or more of the elevated pressure, elevated temperature vapor, the elevated pressure liquid, the reduced pressure liquid, the reduced pressure vapor and combinations thereof, the fluid being monitored with a mechanical resonator.

5. The method of claim 4 wherein the fluid includes a liquid, gas, or combination thereof, selected from refrigerants, refrigerant lubricants, coolants, or combinations of two or more of such fluids.

6. The method of claim 4 wherein the fluid comprises R-134A refrigerant, a mineral oil, an ester lubricant or a mixture thereof.

20. An environmental control system selected from heating, ventilation, air conditioning and refrigeration systems, the system comprising

a passage containing a thermal change fluid, the thermal change fluid comprising R-134A refrigerant, a mineral oil, an ester lubricant or a mixture thereof,

at least one mechanical resonator for relative translation with the thermal change fluid, the mechanical resonator being a flexural resonator, a torsional resonator or a combination thereof, and

a circuit for monitoring a response of the resonator to the thermal change fluid.

21. The system of claim 20 wherein the thermal change fluid includes a liquid, gas, or combination thereof.

22. The system of claim 20 wherein the environmental control system comprises an electronic component environmental control system.

23. The system of claim 20 wherein the environmental control system comprises a motor used to drive a compressor, and the thermal change fluid comprises a fluid used in the compressor motor.

24. The system of claim 20 further comprising a source of an input signal in signaling communication with the resonator, the input signal resulting from an electrical impulse, a mechanical impulse or combinations thereof.

25. The system of claim 24 wherein the input signal is an electrical signal selected from a variable frequency input signal;

a constant frequency input signal;

a voltage spike, a sine wave burst or combinations thereof.

31. The system of claims 20, 26 or 29 wherein the resonator is coated over at least a portion of its outer surface.

32. The system of claims 20, 26 or 29 wherein the resonator comprises a resonator element made of a piezoelectric material.

33. The system of claims 20, 26 or 29 wherein the resonator comprises a resonator element made of lithium niobate.

35. The system of claims 20, 26 or 29 wherein the resonator is selected from tuning forks, cantilevers, unimorphs, bimorphs, membrane resonators, torsion bars or combinations thereof.

36. The system of claims 20, 26 or 29 wherein the resonator is a tuning fork resonator.

37. The system of claims 20, 26 or 29 wherein the resonator is a piezoelectric tuning fork resonator.

38. The system of claims 20, 26 or 29 wherein the resonator is operated at frequencies of less than about 1 MHz.

40. The system of claims 20, 26 or 29 wherein the environmental control system comprises a passenger comfort system of a transportation vehicle.

41. The system of claims 20 or 29 wherein the monitoring circuit further comprises a processing unit adapted to receive a signal from the resonator.

42. The system of claim 41 wherein the monitoring circuit further comprises an amplifier for amplifying the signal from the resonator for receipt by the processing unit.

43. The system of claim 41 wherein the system further comprises a temperature measurement device, and the processing unit is in signaling communication with the temperature measurement device.

26. A superheat monitoring system for use in an environmental control system comprising a refrigerant, the system comprising

at least one mechanical resonator for contacting a superheated refrigerant in the environmental control system, and

a circuit for monitoring a response of the resonator to the superheated refrigerant, the monitoring circuit comprising a processing unit adapted to receive a signal from the resonator, the processing unit being programmed with an algorithm for monitoring the superheat condition of a fluid in the system.

27. The system of claim 26 wherein the monitoring circuit further comprises an amplifier for amplifying the signal from the resonator for receipt by the processing unit.

28. The system of claim 26 wherein the system further comprises a temperature measurement device, and the processing unit is in signaling communication with the temperature measurement device.

30. The system of claims 26 or 29, wherein the refrigerant further comprises refrigerant lubricant.

34. The system of claims 26 or 29 wherein the mechanical resonator is a flexural resonator, a torsional resonator or a combination thereof.

39. The system of claims 26 or 29 wherein the environmental control system is an air conditioning or refrigeration system.

29. An environmental control system, comprising

a compressor for compressing a reduced pressure vapor to form an elevated pressure, elevated temperature vapor,

a condenser for removing heat from and condensing the elevated pressure, elevated temperature vapor to form an elevated pressure liquid,

an expansion device for reducing the pressure of the elevated pressure liquid to form a reduced pressure liquid,

an evaporator for evaporating the reduced pressure liquid to form the reduced pressure vapor,

at least one passage for containing a refrigerant, the refrigerant comprising a fluid selected from one or more of the elevated pressure, elevated temperature vapor, the elevated pressure liquid, the reduced pressure liquid, the reduced pressure vapor, and combinations thereof,

a mechanical resonator positioned to contact the refrigerant in the passage, and

a circuit for monitoring the response of the resonator to the refrigerant in the passage.